random rpm surge........

[mobius maximus]

While sitting at idle ive noticed the engine randomly surges a couple hundred rpm's. Anyone think of any causes/ reasons this may be happening? Thanks

[mnpracing]

My '06 OBV did this when I first bought it (I bought it used). It would also not return to idle speed when I put it in neutral unless I pushed in the transmission lockout and revved it a bit. It turned out to be the black box that the throttle cable connected to in the engine compartment. I forgot what it was called (maybe a "throttlemate"), but if I remember correctly it was about the size of a deck of cards, maybe smaller. It had a lever sticking out of it that connected to the throttle cable. It was about $125.